20 BR or 20-243, or............?

[kenbro]

. hold right on with 100 yard zero and at 200 its 1/4 inch high and at 300 its 3 inches low... just like a lazer ...just a little over 4000fps [ you can go faster if you want, mild load] with a 52 gr berger .:

Are these figures correct?
Regards,Ken.

[Alycidon]

20BR is the way to go, dont worry about the mag feed, just make that first shot count. I even took the ejector out of mine so that I did not loose brass.

A

[NZVarminter]

I might be repeating myself here, as I answered a similar post a week or two ago, but think it was on the 6br site.

I've done a 6br repeater on a left hand Remm 700 short action and am now playing with a 20br on a stiller predator with Rem bottom metal.

Researching on the viability of a BR repeater lead me to conclude it could be done, but in hindsight...its a compromise at best and I doubt any action will load/feed/eject flawlessly.

My R700 6br took quite a bit of mucking around to get it to work. Its not the feeding thats the issue, its the loading and ejecting!

First you start with a 308 mag follower and 223 Z spring. Then do the Whatt modification to put a packer in the back of the mag box and shorten the mag follower.

Then you need to adjust the spring location position in the floorplate so that you get enough upward pressure on the mag follower so that the cases dont dip down when loading and feeding. This takes a bit of trial and error, and cutting spacer to go in front and rear of the spring to create a stop position.

This is quite critical as it effects loading as well. I still have occasional problems when loading the second case and it pushes the first one down and they jam. you then need to open the floorplate and eject them all and start again!@#

Next challenge is the combination of the factory extractor claw and ejector pin. The problem is the br case is so short, that when you pull the bolt back to eject the case, the ejector pin pushes the case neck against the chamber wall. Then as its withdrawn it then runs where the bolt lug recess is, which is wider than the chamber, so the case angle is so sharp that the base of the case looses contact with the ejector pin. So when the bolt is fully withdrawn, the case falls off the bolt face into the mag well!@#$.

The fix for this is to install a Sako extractor which is positioned above the lug, so the case does not run in the lug recess area.

The problem with this fix is that the case now ejects at an upward angle and hits on the scope turret, then falls back into the mag well!@#$%%

The fix to this is to install a small deflector plat to the underside of the weaver rail. NB I had made a cutout in the weaver rail so it didnt obstruct the loading port, and it may be that without the cutout it might have deflected the case before it hits the turret.

Its now feeding and ejecting acceptably, and only the occasional load jam that I live with.

NB my first 6br was on a Tikka T3 with the centre feed mag, and it was much worse! When slowly pushing the bolt forward the case would flick up as the base of the top round slid down the shoulder of the underneath case. The bullet tip would then jam in the corner of the receiver and barrel face.

The other pain with the Tikka is single feeding. The 6br case being short and fat means if you single load and just drop a round in the port, when you push the bolt forward the bullet tip hits the barrel end just below the chamber and stops dead. Then you have to try and get your finger in that pathetically small loading port and jiggle it around to get the tip into the chamber.

My 20Br is on a Stiller Predator action. loading is same issue as the Rem, need to get the feed lips and spring position just right. But the actual chambering is causing problems. I think the bullet tip is catching in the corner of the shoulder of the chamber as it sometimes stops when you push forward. If you pause then repush it then goes in. I suspect its due to the even shorter OAL with the 20BR.

Also have noticed the fluted bolt is shaving brass off the underlying case when it passes over it.

Also noticed you can feel the bolt ride over the underlying case shoulder when withdrawing the bolt too. That 30 deg should has a lot to answer for!

All in all these little things all contribute to a clunky feel when cycling the action.

Have to say I'm not very impressed with the Stiller custom action , not smooth at all, the bolt binds in a couple of locations, due to sharp edges on the bolt and machining marks.

..Doubt I'll try another BR repeater (or Rem action or custom Rem clone) but if I did it would be on a Sako action as they dont have a plunger ejector, so when you pull the bolt back, the case is just sitting centrally on the the bolt face and you can just pluck it off, or eject it, which solves half the problems.

I love the 20 cal for speed and flat shooting, and low recoil so you dont loose your sight picture. The BR case is at the limit of powder capacity for not loosing your sight picture, and I expect a 20-250 would have too much recoil.

Now a 250 thou short 20-250 would have same capacity as the Br and much better feeding.... but the tapered case means you couldnt just shorten the dies so would need custom dies etc so am still pondering on other options.

6.5 Grendel or 6mm AR Turbo all have similar case capacity ot BR case, so they are better options for a repeater.

6.8 SPC case also might be worth looking at, but dont think it has much more capacity than 204 Ruger case.

Hope that helps you decide!

Cheers

Grant

[trotterlg]

This week I should have my factory 6mm BR magazine for the Savage. It will nearly feed from the factory .243 mag, so I will guess that feeding will be good. I have already checked and it ejects the BR case just fine. I also discovered an odd thing with my brass, the neck diameter grows about .0015 after a couple of days. This is with a seated bullet. Only thing I can think is that, because they are Varmint Grenades, that the core is getting compressed some and later expanding the necks. Larry

[ab_bentley]

Larry did you get that reamer yet?


Adam

[trotterlg]

Yes, it came in the mail just an hour ago. Larry

[GLWenzl]

Too late but I vote for the 20 BR, nice choice Larry… I guess that I am in the dark about all the feeding issues but the one I had weaver do on a 700 feeds perfect for me??

Good luck, should give you lots of enjoyment


Click here for video clip of 20 BR feeding

[NZVarminter]

yep seen that vid before, and my rifle will feed just as good as that in a controlled situation. But vary the cycle rate, pause half way through, load a case a little too far forward, any number of things can easily make it hangs up, I guarantee it!

[GLWenzl]

Sounds like a good reason to do another video. I honestly don't remember that much about it so it'll be fun to find out. I only cycled it fast during that clip because someone said they are unreliable for fast follow up shots when calling varmints. Mine is strictly a bench pd gun so feeding is something I don't need or want. Hopefully this weekend I can dig the old gun out, about time for a good clean/lube job anyhow.

[trotterlg]

The Savage 6mm BR magazine arrived today. It is one of the detachable type and my rifle has the blind magazine. The magazines are identical, with the detachable one having a bottom plate that snaps on. I just un-snapped the new one and put it in the blind mag well. No problem at all. It is a 3 round magazine where the .243 was a 4 round mag, the feed lips go further forward and there is a block In the rear to hold the rounds forward. It feeds and ejects great, it will eject both empty and loaded rounds but will not feed an empty case. Looks like life is good, curious about why a 3 round mag, but that is OK. Larry